Draftsman&#39;s instrument



J. V. RICH DRAFTSMANS INSTRUMENT Jan. 4, 1938.

Filed July 25, 1956 [me/25 02 JZC/ Patented Jan. 4, 1938 UNITED STATES PATENT oFFice 2 Claims.

The invention relates to draftsmens instruments or tools and more particularly it relates to instruments or tools combining the principles of a triangle, a protractor, and a plurality of graduated straight edges providing scales, certain of the straight edges having fixed relative angles of inclination and others being relatively rotatable to vary their relations to the other straight edges as desired.

Oneof the objects of the invention is the provision of improvements in instruments of the kind described, whereby such instruments are adapted for use as a thirty-sixty degree triangle, as a forty-five degree triangle and as a protractor, and also provides an arm which may be graduated to form a scale, if desired, the arm being rotatable about a pivot point and adapted to be fastened at any desired angle of inclination relative to the straight edges provided by the triangle, with the arm and triangle adapted to lie fiat upon a drawing table or sheet of paper.

Another object of the invention is the provision of an improved combination draftsmans tool or instrument of the kind described which is durable, relatively inexpensive, simple in operation, and satisfactory for its intended purpose.

Many other objects and advantages of the instrument herein shown and described will be obvious to those skilled in the art from the description herein given.

To this end the invention consists in the novel combination and arrangement of parts herein shown and described and more particularly pointed out in the appended claims.

Referring now to the drawing,

Fig. 1 is a plan View of combination drawing instrument embodying the principles of the in vention; and

40 Fig. 2 is an enlarged scale sectional view along the line 2-2 of Fig. 1.

Referring now more particularly to the drawing, the numeral Ill generally designates a generally triangular shaped plate number preferably consisting of celluloid or of any other suit- 4D able transparent material. The triangular member H] is bounded by perpendicularly extending straight edges I I and I2, the hypothenuse comprising two straight edges I3 and I4. 50 The edge I3 is inclined to the edges l l and 12 at angles of sixty and thirty degrees respectively, and the edge !4 is inclined to the edges H and I2 at an angle of forty-five degrees. The described bounding edges of the member l0 adapt it to be used as a thirty-sixty degree triangle and also as a forty-five degree triangle. The member I0 is graduated adjacent its bounding edges to form scales, the graduations shown being in inches andfractions thereof and are typical only. One face of the triangular plate member Ill provides an arcuate quadrant Vernier l5 graduated in both directions and on the inside of the vernier the plate member provides an arcuate slot i6.

An elongated member I], preferably constructed of aluminum or similar light 'metal, is rotatable relative to the plate member ID. The member I! comprises a pair of perpendicularly extending arms l8 and I9. The arm 18 is bounded by parallel straight edges and extends along the edge 12 of the plate memberlll, the arm and plate member both being adapted to have their lower faces in contact with the drawing sheet or board. The arm l9 projects over the member ID and is fastened to the latter by a pivot member 20 projecting through a metallic sleeve sleeve 24 carried by the member ID. The arm !9 is clamped between a head 22 and countersunk shoulder 23 formed on the pivot member 20. The lower end of the sleeve 24 is tapered to receive a countersink for the correspondingly tapered end of the pivot member 20. An annular metallic washer 25 provides a spacer between the plate member l8 and arm I9 adjacent the pivot member 20, the construction of the pivot member and of the sleeve 24 being such that the bearing parts are all metal and there is no wear on the material comprising the plate member in.

The arm l9 overlaps the arm 18, the arms be ing rigidly connected by a plurality of rivets 26. 3

The free end of the arm l9 has a central groove 21 forming a pointer and shown in alignment with one of the end graduations comprising the Vernier l5, in which position the arm I8 extends along and coincides with the edge [2 of the member Hi. The arms 13 and I9 are adapted to be fastened either in the full line position shown, or at any selected angle of inclination of the arm i8 relative to the edge l2, as shown in dotted lines, the selected angle being indicated by the reading of the pointer 2'! on the Vernier 5. The fastening means comprises a bolt 28 carried by the arm is. The head of the bolt 28 is positioned in and movable along the lower enlarged portion of the slot IS. The other end of the bolt 28 is threaded to receive a knurled head or knob 29. A pair of washers 30 separate the arm l9 from the knob 29 and the plate member ID respectively and serve thereby to re-enforce the plate member when the arm is clamped between the washers by manipulation of the knob. The knob 29 is loosened when it is desirable to change the angle of inclination of the arms l8 and I9 and is easily tightened'to hold the arms at any selected reading on the Vernier IS.

The sleeve 24, the rivets 26, and the head of the bolt 28 are all countersunk as described in order that the lower face of the plate member ID and of the arm I8 may be flush with the drawing board or sheet of paper. The described construction of the combination instrument provides novel means for drawing lines at the more frequent angles of inclination such as thirty, fortyfive, sixty and ninety degrees, and combines, with a triangle, providing straight edges having all of the suggested fixed relative angles of inclination, a rotatable straight edge and a protractor adapted to indicate any angle of inclination of the rotatable straight edge from zero to ninety degrees.

Having thus described my invention it is obvious that various immaterial modifications may be made in the same without departing from the spirit of the invention; hence I do not wish to be understood as limiting myself to the exact form, construction, arrangement and combination of features herein shown and described or 7 uses mentioned.

I claim:

1. A drafting instrument of the kind described comprising a triangle body, an elongated member comprising a pair of arms angularly related to each other, one of said arms overlapping and the other extending along one edge of the triangle body, a pivot extending through and connecting the overlapping arm with said body, said. overlapping arm providing a groove or the like adapted as a pointer and the upper face of said body providing an arcuate scale for cooperation with the pointer, said pivot having its lower end countersunk Within the body and the arm extending along one edge of the body having its lower face in the same plane as the lower face of the body whereby rotation of the pointer along the arcuate scale correspondingly moves the other arm over the surface on which the triangle body is positioned.

2. A drafting instrument of the kind described comprising a triangle body, an elongated member comprising a pair of arms angularly related to each other, one of said arms overlapping and the other extending along one edge of the triangle body, a pivot extending through and connecting the overlapping arm with said body, said overlapping arm providing a, pointer and the upper face of said body providing an arcuate scale for cooperation with the pointer, said pivot having its lower end countersunk within the body and the arm extending along one edge of the body having its lower face in the same plane as the lower face of the body whereby rotation of the pointer along the arcuate scale correspondingly moves the other arm over the surface on which the triangle body is positioned, said body providing an arcuate slot and arcuate extensions of the slot on its underside concentric with said Divot, a bolt positioned in the slot with its lower end providing a head movable within said extensions of the slot and its upper end connected with said overlapping arm, and means operable to clamp the bolt to said body tolock said arms against rotation at any selected reading of the pointer on the arcuate scale. 1

JACK V. RICH. 

